Recent work, especially in the yeast Saccharomyces cerevisiae, has demonstrated that mRNA movement from active translation to cytoplasmic granules, termed mRNA processing bodies ("p-bodies"), occurs in concert with the regulation of translation during cell stress. However, the signals regulating p-body formation are poorly defined. Recent data demonstrated a function for sphingolipids in regulating translation during heat stress, which led to the current hypothesis that p-bodies may form during heat stress in a sphingolipid-dependent manner. In this study, we demonstrate that mild heat stress induced formation of p-bodies as determined by localization of a GFP-tagged Dcp2p and RFP-tagged Edc3p to discrete cytoplasmic foci. Sphingoid base synthesis was required for this effect, as inhibition of sphingoid base synthesis attenuated formation of these foci during heat stress. Moreover, treatment of yeast with exogenous sphingoid bases phyto- and dihydrosphingosine promoted formation of p-bodies in the absence of heat stress, and the lcb4/lcb5 double deletion yeast, which accumulate high intracellular levels of sphingoid bases, demonstrated large, clearly defined p-bodies under non-stress conditions. Functionally, inhibition of sphingolipid synthesis during heat did not prevent translation stalling but extended translation arrest, indicating that sphingolipids mediate translation initiation. These data are consistent with the notion that p-bodies serve not only for mRNA degradation, but also for re-routing transcripts back to active translation, and that sphingolipids play a role in this facet of the heat stress response. Together, these data demonstrate a critical and novel role for sphingolipids in mediating p-body formation during heat.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Annotation Extension||Reference|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Assay||Construct||Conditions||Strain Background||Reference|